Internal combustion engine



July 14, 1931. 2. s. HOFFMAN 1,313,925

INTERNAL COMBUSTION ENGINE Filed May 21. 1929' 2 Sheets-Sheet l K INVENTOR.

Zachafldb fl/Yim ATTORNEY July 14, 1931. z s, HOFFMAN 1,813,925

INTERNAL COMBUS TION ENGI NE Filed May 21. .1929 2 Sheets-Sheet 2 Ln N S INVENTOR. ZQCYfl/"lbb ATTORAI Y Patented July 14, 1931 ZACHARIAH S. HOEFIEIAN, OI ESSEX COUNTY, N'EFW JERSEY INTERNAL COMBUSTIGIE ENGINE i Application filed-Easy 21, 1923. Serial No.

My invention relates to improvements in internal combustion engines and has for one object to provide for substantially complete scavenging of the products of combustion.

Itis a common practice to compress the fuel charge of'an internal combustion engine to about one-fifth of its original volume before firing takes place. In other words, the firing chamber or clearance between the cylinder head and the piston when the latter is at the limit of its compression stroke is equal to about one-quarter of the displacement of the piston. While the clearance is necessary to .allow for proper compression of the fuel mixture, it prevents complete scavenging of the cylinder and each fresh charge is diluted with a large proportion of inert gas. On a wide open throttle the dilution amounts to about per cent and as the fuel mixture is 20 thinned down by the throttle valve the dilution is proportionately greater. Automobile engines and even airplane engines are seldom run on a wide open throttle, with the result that dilution of the charge due to incomplete scavenging assumes serious proportions resulting in incomplete combustion and a lowering of engine efliciency. Furthermore, theburnt gases are apt to be densest about the firing plug causing uncertainty of firing and fouling of the spark points.

The foregoing disadvantages of present common practice have been recognized and many expedients have been tried to effect complete scavenging. I am aware that engines have been built with movable cylinder heads, or in other words, with an auxiliary piston or plunger head to take the place of a fixed cylinder head, which plunger head was arranged to advance and meet the working piston during the exhaust stroke so as to displace all the products of combustion. In some cases the plunger head was operated by a crank arm, in others by an eccentric and in still others by a cam to force the plunger head inward and a spring to make it follow the cam outward. These various constructions have failed of general adoption for various reasons, such as complication of mechanism, uncertainty of operation, etc.

It is an object of my invention to provide an improved internal combustion engine of the above general type in which the plunger head is positively operated in timed relation to the working piston. Thus, in a preferred embodiment of my invention, I dispense with all springs by using opposed cams acting on the plunger head to move it positively in andout. In other words, a follower cam serves to hold the plunger in positive engagement at all times with the working cams.

Another object of my invention is to provide for more than a mere in-and-out motion of the plunger head. Thus in a four-cycle engine the plunger head remains fixed during the compression and firing strokes and on the exhau st stroke advances to meet the working piston, while on the intake stroke the plunger head recedes to a point well beyond its compression and firing position. Thus not only is the cylinder charged with a clean fuel mixture uncontaminated by'burnt gases, but it also takes in a charge of greater volume than is possible in engines as heretofore constructed, with a greater relative compression. As a result more power may be. developed than in other engines of the same stroke and.

bore.

Another object of my invention is to provide a very simple and readily accessible means of taking up wear in the cam operated mechanism. 7

- Another object of my invention is to provide an improved valve mechanism operating in conjunction with the plunger'head. To this end, I employ a'slide valve which is operated by opposed cams carried on the same shaft as that which carries the cams that operate the plunger head.

' Still another obiect of the invention is to provide a slide valve which will be self-seating, thereby avoiding the periodic grinding which is necessary in the ordinary valve constructions.

Still another object of the invention is to provide a simple means of adjusting a slide valve against its seat so as to take up wear, this adjustingmeans being operable from a convenient point outside of the engine so that no parts need to be dismantled when adjusting the valve. I

Other objects and advantages of my invention will appear in the following description of a preferred embodiment of my invention and therefore the novelty and scope of my invention will be pointed out in the claims.

In the accompanying drawings:

Figure 1 is a view in transverse section through my improved internal combustion engine, the section being taken on the line 11 of Fig. 2;

Fig. 2 is a side view of a portion of the engine with the intake and exhaust manifolds removed;

Fig. 3 is a fragmentary plan View of the engine with a portion thereof broken away and certain parts in section Fig. 4 is an enlarged fragmentary sectional view of the upper portion of the engine, the section being taken substantially on the line 44 of Fig. 1;

Fig. 5 is a View in perspective of the plunger head and certain associated parts.

In the accompanying drawings I show a multiple cylinder engine having a cylinder block preferably formed of an upper section 10 and a lower section 11. These sections are fastened together by means of bolts or long screws 12. The lower section 11 is secured by suitable means to a crank case 13, while supported on the top of the upper section 10 is a bracket member 14 preferably made fast to the engine by the screws 12-.

The cylinder block is formed with cylinders 15 which extend through the upper and lower sections 10 and 11 and which are provided with water jackets 16 in the usual manner. A working piston 17 is fitted in each cylinder 15 and preferably operates only in the lower section 11 of the cylinder block. Each piston 17 is provided with the usual connecting rod'18 connected to a crank shaft 19 journaled in the crank case. The crank shaft is provided at one end with a sprocket wheel 20 which is connected by a silent chain to a sprocket wheel 22 secured to a cam shaft 23. The cam shaft is journaled in bearings'24 carried by the bracket member 14. The sprocket wheel 22. is double the diameter of the sprocket wheel 20 so that the cam shaft will rotate at one-half the speed of the crank shaft.

Mounted to reciprocate in each cylinder 15 above the working piston is an auxiliary pisten or plunger head 25. This plunger head is provided at its upper end with a shank consisting of a pair of spaced vertical plates 26 which are seated at their lower ends in grooves 27 formed in the upper face of the plunger head 25. The plates are clamped to the plunger head 25'by means of a pair of screws 28. The head of each screw enters a pair of arcuate recesses 29 formed respectively in the opposite plates 26, so that as the screws are screwed home they will draw down the plates and clamp them tightly in the grooves 27. Each plate 26 is bifurcated with a space 30 between the furcations through which passes the cam shaft 23. At their upper ends the arms are securely fastened to a spacer block 31. Clamped to the spacer block and fitted between the furcations of the plates 26 are plates 32 which, near their lower ends provide journals for a pin 33 on which is supported a roller 34. This roller is adapted to engage a cam 35 located between the plates 26 and keyed. to the shaft 23.

In order to take up wear, means are provided for adjusting the roller 33 with respect to the cam 35. To this end, the plates 32 are clamped to tne block 31 by means of screws 36 which pass through elongated slots 37 in the block 31. a The plates 32 project slightly above the top of the block 31 and are formed on their inner faces with arcuate recesses 38 to receive the head of a screw 39 which is threaded into the upper end of the block 31. Thus by loosening the screws 36 and tightening the screw 39 the plates 32 will be forced downward, adjusting the position of the roller 34 with respect to the cam 35, and after the adjustment has been made the screws 36 are tightened, with the result that not only is the roller held at the adjusted position, but the screw 39 is also clamped against turning by the plates 32.

The block 31 is arranged to reciprocate in guideways formed in a pair of guide members 40 which are secured to extensions 41 of the bearing members 24. Journaled in the guide members 40 are rollers 42 which bear against opposite sides of the block 31. The purpose of this guide mechanism is to relieve the plunger head 25 from lateral strain as it is reciprocated, thus insuring even wear of the plunger head in the cylinder. In addition to the cam 35 on the cam shaft 23 there are two other cams 43 keyed to the cam shaft on opposite sides of the plunger shank. These cams 43 engage rollers 44 carried by the plunger head. The rollers are j ournaled on a pin 45 which passes through the plates 26 and is supported in lugs 46 formed on the upper face of the plunger head.

It will be observed that rollers 44 bear against the lower edge of the cams 43, while the roller 34 bears against the upper edge of the cam 35. The latter cam is a follower cam which is so profiled as to maintain the rollers 44 always in contact with and under control of the cams 43. When the screw 39 is adjusted to take up wear, not only is the roller 34 moved down against the cam 35, but the rollers 44 are drawn up against the cams 43.

The cams 43 and 35 are of such shape that on the intake stroke of the working piston 17 the plunger head 25 will be raised to a predetermined point so as to draw in a large volume of fuel mixture. On the compression stroke the plunger head 25 will be lowered to a point which will givea desirable firing space in the cylinder. Inthis-position, the

plunger head will remain while the charge is fired and the working piston 17 is on its expansion stroke, but during the exhaust stroke, as the working piston moves upward, the plunger head will move downward approximately to the dividing line between the sections and 11. The working piston 17 also rises to approximately the same line and con sequently substantially all of the products of combustion will be displaced from the cylinder.

'As shown in Fig. 1, a spark plug 47 is provided at one side of the cylinder at a point slightly above the dividing line between the two cylinder block sections, and a common intake and exhaust port 48 is provided on the other side of the cylinder between the two sections, the port being formed in a depending extension 10a of the upper section.

To control the admission of the charge and the exhaust of burnt gases, I employ a slide valve for each cylinder. To this end, the cylinder block is provided with a valve seat 49 opposite each cylinder, against which a slide valve 50 is fitted. Partition walls 49a separate the valve seats of the several cylinders. Each slide valve is provide-d with a pair of ports 51 and 52 respectively, which, as the valve 50 is reciprocated, alternately connect the port 48 with an intake manifold 53 and an exhaust manifold 54.

As shown in Fig. 2, the ports 51 and 52 and the port 48 extend across almost the entire width of the cylinder, so as to provide a very wide opening for the admission and exhaust of fluid to and from the engine. The exhaust and intake manifolds are formed in a single casting 55 which is bolted to a suitable facing 56 formed on the cylinder section 10 and "extension 10a. In order to adjust for wear of the slide valves against the seat 49, I provide a take-up plate 57 for each valve, which is fitted between the slide valve and the casting 55. The takeup plate is formed with ports 58 and 59 which are alined with the ports leading to the intake and exhaust manifolds respectively. The outer face of the take-up plate is formed wit-h pads or bosses 60 which fit into corresponding recesses in .the inner face of the casting 55, and the upper and lower walls of the bosses and recesses serve as seals against leakage as the take-up plate is moved inward against the slide valve. To adjust the take-up plate 57, a pair of screws 62 are threaded through the casting 55 and bear against the take-up plate. These screws are provided with lock nuts 63 to hold the take-up plates at desired adjustment. At each end of the valve seat 49 there is a shallow groove 64 which serves to prevent the valve from wearing a shoulder in the valve seat. Similarly the take-up plate 57 is provided with shallow grooves 65 at its upper and lower ends to prevent the wearing of shoulders thereon by the valve.

To operate the valve 51, I employ a rocker arm 66 which is pivoted on a stud 67 projecting from an adjacent bearing member 24. This rocker arm carries a-pair of rollers 68 and 69 respectively. These rollers are adapted to engage cams 7 O and 71, respectively, secured to the cam shaft 23. The rocker arm 66 is connected by a link 72 to a stem 73 which passes through the casting 55, and is threaded into the slide valve 51. The cam 71 serves to raise the slide valve while the other cam 7 0 serves to depress the slide valve. These cams are so relatively disposed that they are always in engagement with rollers 68 and 69 respectively. Hence the slide valve is always under positive control of the cams. The arrangement is such that immediately after the slide valve has been raised so as to connect the intake manifold with the port 48 and a complete charge has been introduced into the cylinder, the valve will close quickly by moving to intermediate position where neither the port 51 nor the port 52 will communicate with the port 48. In this position, the ports will remain until the piston is on its exhaust stroke, when the cams will operate the slide valve to connect the port 48 with the exhaust manifold 54 and as soon as complete exhaustion of the gases has taken place the valve will again move quickly to the intake position connecting the port 48 with the intake manifold 53. By employing opposed cams to operate the slide valves springs are dispensed with. The valves may be moved very quickly from one position to another, providing a sudden and wide opening of the port 48 either to the intake or to the exhaust manifold as the case may be.

One of the advantages of my construction lies in the accessibility of the various'parts. The valves require no grinding and because of complete scavenging there will be practically noaccretions of carbon in the valve passages. The valves, as they wear, may be tightened up very readily without dismant-ling any part of the engine by simplyloosening the lock nut 63 and tightening the screws 62 after which the adjustment may be maintained by again tightening the lock nut 68. \Vhenever it is desired to gain access to the interior of the cylinders, the entire upper.

portion of the engine block with the valve casing may be removed after unscrewing the bolts 12.

lVhile I have described a preferred embodiment of my invention it will be evident that various changes may be made in form, construction, and arrangement of parts, without departing from the spirit and scope of my invention as pointed out in the following claims.

I claim: r

1. In an internal combustion engine, a cylinder, a pistonreciprocable therein, the cylinder having a port therein, an intake conduit, an exhaust conduit, a slide valve normally closing the port, means drivenby the piston for moving the slide valve in one direction to connect the port with the intake conduit on the intake stroke of the piston and in another direction to connect the porn with the exhaust conduit on the exhaust stroke of the piston, and means for positively taking up wear of the slide valve.

2. In an internal combutsion engine, a cylinder having a port therein, a piston reoiprocable in the cylinde a valve normally closing said port, a casing for the valve, said casing being formed with an intake conduit and an exhaust conduit, means for reciprocating the valve to connect the port with said conduits in alternation, said means being driven in timed relation to movements of the piston, a take up plate between the valve and the casing, and means for adjusting the plate to take up wear of the valve.

3. In an internal combustion engine, a cylinder formed with a port, a piston reciprocable in the cylinder, a valve normally closing said port, a casing for the valve, said casing being formed with an intake conduit and an exhaust conduit, means for reciprocating the valve to connect the portwith said conduits in alternation, said means being driven in timed relation to movements of the piston, a take up plate in the casing and bear ing against the valve, and means for adjusting the plate to take up wear of the valve, the take up plate and the casing being provided with coacting shoulders to prevent leakage from one conduit to the other.

4. In an internal combustion engine, a cylinder, a piston reciprocable therein, the cylinder being formed exteriorly with a flat valve seat and a port opening therethrough, a fiat valve plate slidable on the seat and formed with an intake passage and an exhaust passage therethrough with a land between the passages normally closing said port, a casing for the valve and secured to the cylinder, said casing having an intake conduit and an exhaust conduit formed therein, means operating in timed relation to the piston for sliding the valve to connect the port with the intake conduit and the exhaust conduit in alteration, a wear plate between the valve and the conduit and formed with openings connecting respectively with the intake and the exhaust conduits, and means for adj usting the wear plate toward and from the valve.

5. In an internal combustion engine, a cylinder, a piston reciprocable therein, the cylinder being formed exteriorly with a flat valve seat and a port opening therethrough, a fiat valve plate slidable on the seat and formed with an intake passage and an exhaust passage therethrough with a land between the passages normally closing said port, a casing for the valve and secured toflthe cylinder.

said casing having an intake conduit and an exhaust conduit formed therein, means operating in timed relation to thepiston for sliding the valve to connect the port with the intake conduit and the exhaust conduit in alternation, a wear plate between the valve and the conduit and formed with openings connecting respectively with the intake and the ex haust conduits, and means for adjusting the wear plate toward and from the valve, the casing and the wear plate being formed with coacting shoulders to prevent leakage from one conduit to another.

6. In an internal combustion engine, a cylinder block transversely divided into two sections removably connected together and combining toform a working chamber, a piston in said chamber and reciprocable in one of the sections, an extension on the other section overlapping the first section, said extension being formed exteriorly with a valve seat and a port opening therethrough into the working chamber, a valve plate slidable on said seat and formed with an inlet passage and an outlet passage therethrough, a casing for the valve having an intake conduit and an exhaust conduit formed therein, said casing being secured to the extension, and means driven by the piston for sliding the valve whereby said intake passage will connect said 9 port with the intake conduit on the intake stroke of the piston and the exhaust passage will connect said port withthe exhaust conduit on the exhaust stroke of thepiston.

In testimony whereof, I have signed this specification.

ZACHARIAH S. HOFFMAN. 

